3 link vs 4 link

[mazspeed]

Ok guys I have some questions on both systems. When I rip the car back apart at years end I would like to know what system is best. I have some questions on both. First the Dynamics 3 link. How much of the rear seat will still be useable? It looks from the install pictures that you almost have to rid the rear seat, but it's hard for me to tell. Another point, I have enclosed a picture of the lateral load bolt that I was curious about. http://www.tri-phase-electric.com/rear.jpg
My questions are these. Is that bolt holding the entire unit from going to each side? To me it seems a bit scary that the entire rear is being held in place with this bolt. Also like my Comp bars, the end links seem to hang a little low as well. Also can you run any kind of rear end, or do you have to run a certain carrier? I see in all pictures that I have seen run the same carrier? It also seems like twice the fabrication for this system then a 4 link? Am I wrong?

Ok now the DSE system. I know a little bit about this already other then the new piece that is now coming in for the fix from the original design. Does anyone have a photo of this piece, and how does it connect to the system? How strong are these swivel links? How do they affix to each other? The top 2 links on the DSE seem very short, is this any kind of control issues with this design? Also the panhard bar that they use in the DSE system to keep the side from going back and fourth seems small. Also what about the rear seat? I will tub the car, so I know that the rear seat will have to again be modified, but I don't think, well really don't know if the DSE system will be as intrusive as the 3 link as far as the rear seat goes. Any ideas on that? I know that with the DSE system and when I tub it, I won't lose my custom gas tank, is this the case for the 3 link??
I don't mean to nit pick each system, but I have to for my own gain. I think both systems are the best in the business from where I stand and I need to know which is best for me. I can drive better then most, but cannot design anything other then custom lighting, so I'm at a loss, so this is why I ask. Sorry it's so long winded guys.

[Matt@Lateral Dynamics]

Ok guys I have some questions on both systems. When I rip the car back apart at years end I would like to know what system is best. I have some questions on both. First the Dynamics 3 link. How much of the rear seat will still be useable? It looks from the install pictures that you almost have to rid the rear seat, but it's hard for me to tell. Another point, I have enclosed a picture of the lateral load bolt that I was curious about. My questions are these. Is that bolt holding the entire unit from going to each side? To me it seems a bit scary that the entire rear is being held in place with this bolt. Also like my Comp bars, the end links seem to hang a little low as well. Also can you run any kind of rear end, or do you have to run a certain carrier? I see in all pictures that I have seen run the same carrier? It also seems like twice the fabrication for this system then a 4 link? Am I wrong?
1) You will need to run a split-bun type of rear seat with our kits. See attached picture.

2) Yes, the bellcrank and it's bolt and bearing are what holds the rear end laterally in the car. The bolt is a class 10.9 M20-2.5 and has an approximate shear strength of 36,500psi, and the bellcrank itself is made out of 2024 T6 aluminum, and was proven in FEA at 6,000psi in yield. Mark's had the prototype, which is a slightly inferior design, on his car for nearly two years now with absolutely no problems. Beyond that, this same Watt's setup and it's variations have been on extremely fast road race cars for many years. This is not a new design, we just adapted it to our likeing.

3) The LCA brackets on our rear ends will be off the ground by 4 5/8" with a 335/30/18 tire. This is a bit low, but we're not designing 4x4 suspensions either. That height was arrived at in order to get the excellent geometry we built into these suspensions. Ground clearence was kept in mind throughout the design process, however it mainly took a back seat to performance.

4) We supply fully welded 9"s with each kit, and this is the only option. The 9" is the obvious choice when you consider the fact that you can't reliably weld an UCA bracket to a cast iron housing. That, and the huge amount of aftermarket support for the 9". You can run any factory or aftermarket 3rd member you choose.

5) We tried our best to make this kit as easy to install as possible, but at the same time, we refuse to make huge compromises in geometry and function for the sake of a "bolt-in" kit. We realise that this will drive some potential customers into the arms of our competitors, and that's ok.

[customcam]

Is there a limit on how heigh the wheels can be? say a 19 or 20 inch rear wheel?

[Matt@Lateral Dynamics]

20's on a B body Mopar. ;)

http://www.lateral-dynamics.com/gallery/plum_floored/Mopar06.jpg

http://www.lateral-dynamics.com/gallery/plum_floored/Mopar01.jpg

[murtah]

The "new" part for DSE's Quadra link is a reiforcement for the Pan hard bar bracket on the pass side frame rail. The attached letter states that if you use your car on the track, the reinforcement is recommended. They discovered this recently when they were testing the rear on a track.

You can still use your stock rear seat but you need to trim some of the springs on the bottom as well as the upper sides for the mini tubs.

[Dodgenut64]

wow nice B body, got anymore pics?

[4mm]

Mark, is that the Mopar you told me about that was built in SA?

[Matt@Lateral Dynamics]

wow nice B body, got anymore pics?
http://www.lateral-dynamics.com/gallery/plum_floored/

[Mean 69]

Mark, is that the Mopar you told me about that was built in SA?

Yep, that's her. Pretty cool car, some really nice body mods, it's mean looking for sure. Really neat FI unit for the 6.1 HEMI engine too.

Mazspeed, take a look at our site for more info on the setup, if you haven't already (which it appears that you have), we tried to include a good amount of content to help explain our design approach. You already nailed it, this isn't a bolt in affair, in our educated and professional opinion, it's not a viable possibility due to the packaging constraints these cars have. We could have made a bolt in deal, but the performance compromises associated with that option are not ones that are not acceptable to us.

One clear point that sets our setup apart from every other unit out is the length of the control arms, as you noted. This was done with our eyes wide open, based upon the results of countless mathematical results, testing with our own car, and exhaustive research with folks that have been there, and done that (with a big emphasis on amateur and professional road race teams/engineers). At some point, you reach a point of diminishing returns, but longer is better, the physics say so. Stick axles need to be able to move up and down quite a bit to provide the most grip under a variety of circumstances, and as they move, the critical suspension geometry parameters change. The rate at which they change is directly proportional to the length of the links.

I have not personally installed the DSE system, but as you can imagine, I have seen several pictures of it. In relative terms, there might be a bit more work to install our setup, but it's not significant, it's actually a LOT easier if you construct your own rear housing, our setup comes with a completed fully welded housing. The main difference is that we insist loads be reacted through a rigid crossmember, our forward crossmember is probably the most tedious part to install, not hard, just tedious. If you have the ability to install a set of through floor subframe connectors, or if you are going to take on a mini-tub job, you can handle the installation of this kit.

Whatever you decide, have a great time with your car and enjoy the journey!

Best of luck,
Mark

[68protouring454]

here is a shot of how low the lca brackets are, which really are not that low, my car will be one of the lower cars with the 3 link in it and there is plenty of room, this kit can be installed in the same amount of time or less then a set of mini tubs with closeouts,
think about it, when one side of an axle goes into bump, it wants to go up and in towards the center of the car, so imagine the axle trying to do this with a 4 link whether it has swivels or not, it will bind, the swivels help it but the uper link just will not let the axle move smoothly, now think about it with a 3 link, it as good as it gets with a stick axle,
http://img204.imageshack.us/img204/804/carheadintogetcage0016pp3iq.jpg (http://imageshack.us)
this is a shot of clearance, althought he car looks high the roof is 49 inches off the ground, and theres 6 inches to 5 inches the bottom of the rear end.

[mazspeed]

Wow guys, thank again for all the answers on this. I'm going to seriously consider the 3 link highly when it's time to tear it back down again.

[Steve1968LS2]

Wow guys, thank again for all the answers on this. I'm going to seriously consider the 3 link highly when it's time to tear it back down again.

When mine is done you can take it for a spin (not litterally.. lol) and see how you like it.

Both systems have their pluses and minus's.. I sorta hate to make it a "A vs B" deal..

The LD kit wasn't that tough to put in.. About a 7 on a scale of 1 to 10..

[mazspeed]

When mine is done you can take it for a spin (not litterally.. lol) and see how you like it.

Both systems have their pluses and minus's.. I sorta hate to make it a "A vs B" deal..

The LD kit wasn't that tough to put in.. About a 7 on a scale of 1 to 10..

That good to hear Steve. You don't mind me doing some heal and tow stunt driving in your car do you? :willy:

I had a watts system in my race 7's I used to drive, and they held up fine, granted this is more weight and a lot more power. :unibrow:

[Ummgawa]

I'd run the Martz 4 link I currently have if I could get some of the Swivel links from DSE. Don't get me wrong...I can get a full set, for 1400 dollars, they will even throw in the set up with it (minus coil overs of course). LOL.

[tyoneal]

Mark:

With regards to your 3-Link, what would be the Pros and Cons to it over a IRS?

Will the Narrowed Tank that DSE sells to go with their Wheel Tubs, work ok with your 3-link?

If someone wants the exhaust out the back, would you recommend cutting a route for it when the wheel tub are going in? (Putting it through the trunk and then covering it with sheet metal)

Thanks,

tyoneal

[Mean 69]

Great questions, Ty, they look familiar! I promise I'll respond to your e-mail, by the way, I'm a little bit behind.

The main benefit of the 3-Link over an IRS is the simplicity (well, that's relative, because there is a LOT that went into our own design that isn't present in any of the other commercial applications we have seen that has a dramatic impact on the overall performance). IRS systems can clearly be made to work very well, but more often than not (and this hold mainly true for the aftermarket but also on several contemporary factory designs), something's not right and the performance of the setups suffer big time. IRS is better on bumpy tracks, but on smooth tracks, there isn't much of an advantage. IRS is usually heavier overall than a stick axle, but the stick axle suffers from higher unsprung weight. One benefit of the higher unsprung weight is that ability to tune the system and take advantage of the higher inertia of the stick axle, by employing relatively high levels of anti-squat. IRS systems are limited by the physics of the approach to roughly 25% or so anti-squat, and usually this comes at the expense of other important suspension geometry issues. With a stick axle, you can get well over 100% A/S with certain configurations, but here again, this virtually always comes at the expense of potential for violent brake hop (anyone catch the Sears Point NASCAR race over the weekend, and note the commentary on wheel hop going in to the hairpin? They had some GREAT footage, and also did a small tech explanation with the cutaway car.). There are pro's and con's to either setup, that for certain. It'd be interesting to do a direct comparison between a "good" IRS system and our current 3-Link, that's something we'll likely do in the future, but for now, we are working on applying the same engineering rigor that we did on the rear suspension to the front. That, and adapting the 3-Link to early Mustangs, Nova's, E-Body Mopars, and A-Body GM cars. Oh, and building, shipping, and installing systems too. We're a little busy, but it's terrific.

There is no reason you'll need to get a different fuel tank, the system works even with the stock tank, so you will be fine. It is important to note though, that like one of our competitor's suspension systems, in order to run tailpipes out the back, the forward corners of the gas tank will need to be notched.

If you are working on a first gen F body car, there is a bit of sheet metal work that will need to be done in the trunk area, if you look at the installation page on our website (www.lateral-dynamics.com), you can see what that entails. You can tub the car before, during, or after the install of our kit, there is no conflict between the two.

Hope that helps!
Mark